| Clue | Source | Date |
|---|---|---|
| Tones for jeans | ||
| Plants that yield a blue dye | New York Times | 10 Nov 2019 |
| Plants that yield a blue dye | ||
| Blue hues | New York Times | 05 Jun 2017 |
| Blue hues | ||
| Dyes used for blue jeans | LA Times Daily | 27 Mar 2016 |
| Blue hues | ||
| Blue dyes | ||
| Spectrum colors | ||
| Shades of blue | ||
| Blue dyes | ||
| Blue dyes | ||
| Blue dyes. |